A Hoffa fracture is a fracture of the coronal plane of the femoral condyle. It was first described by Friedrich Busch in 1869 and was reported again by Albert Hoffa in 1904, and was named after him. While fractures usually occur in the horizontal plane, Hoffa fractures occur in the coronal plane and are very rare, so they are often missed during the initial clinical and radiological diagnosis.
When does a Hoffa fracture occur?
Hoffa fractures are caused by shear force to the femoral condyle at the knee. High-energy injuries often cause intercondylar and supracondylar fractures of the distal femur. The most common mechanisms include motor vehicle and motor vehicle accidents and falls from height. Lewis et al. pointed out that most patients with related injuries were caused by direct impact force to the lateral femoral condyle while riding a motorcycle with the knee flexed to 90°
What are the clinical manifestations of Hoffa fracture?
The main symptoms of a single Hoffa fracture are knee effusion and hemarthrosis, swelling, and mild genu varum or valgus and instability. Unlike intercondylar and supracondylar fractures, Hoffa fractures are most likely to be discovered incidentally during imaging studies. Because most Hoffa fractures result from high-energy injuries, combined injuries to the hip, pelvis, femur, patella, tibia, knee ligaments, and popliteal vessels must be excluded.
When a Hoffa fracture is suspected, how should one take X-rays to avoid missing the diagnosis?
Standard anteroposterior and lateral radiographs are routinely performed, and oblique views of the knee are performed when necessary. When the fracture is not significantly displaced, it is often difficult to detect it on radiographs. On the lateral view, a slight discordance of the femoral joint line is sometimes seen, with or without condylar valgus deformity depending on the condyle involved. Depending on the contour of the femur, a discontinuity or step in the fracture line can be seen on the lateral view. However, on a true lateral view, the femoral condyles appear non-overlapping, whereas if the condyles are shortened and displaced, they may overlap. Therefore, an incorrect view of the normal knee joint can give us a false impression, which can be shown by oblique views. Therefore, CT examination is necessary (Figure 1). Magnetic resonance imaging (MRI) can help evaluate the soft tissues around the knee (such as ligaments or menisci) for damage.
Figure 1 CT showed that the patient had a Letenneur ⅡC type Hoffa fracture of the lateral femoral condyle
What are the types of Hoffa fractures?
Hoffa fractures are divided into type B3 and type 33.b3.2 in the AO/OTA classification according to Muller’s classification. Later, Letenneur et al. divided the fracture into three types based on the distance of the femoral fracture line from the posterior cortex of the femur.
Figure2 Letenneur classification of Hoffa fractures
Type I: The fracture line is located and parallel to the posterior cortex of the femoral shaft.
Type II: The distance from the fracture line to the posterior cortical line of the femur is further divided into subtypes IIa, IIb and IIc according to the distance from the fracture line to the posterior cortical bone. Type IIa is closest to the posterior cortex of the femoral shaft, while IIc is farthest from the posterior cortex of the femoral shaft.
Type III: Oblique fracture.
How to formulate surgical plan after diagnosis?
1. Internal fixation selection It is generally believed that open reduction and internal fixation is the gold standard. For Hoffa fractures, the selection of suitable fixation implants is quite limited. Partially threaded hollow compression screws are ideal for fixation. Implant options include 3.5mm, 4mm, 4.5mm and 6.5mm partially threaded hollow compression screws and Herbert screws. When necessary, suitable anti-slip plates can also be used here. Jarit found through cadaver biomechanical studies that posteroanterior lag screws are more stable than anterior-posterior lag screws. However, the guiding role of this finding in clinical operation is still unclear.
2. Surgical technology When a Hoffa fracture is found to be accompanied by an intercondylar and supracondylar fracture, it should be given enough attention, because the surgical plan and the choice of internal fixation are determined based on the above situation. If the lateral condyle is coronally split, the surgical exposure is similar to that of a Hoffa fracture. However, it is unwise to use a dynamic condylar screw, and an anatomical plate, condylar support plate or LISS plate should be used for fixation instead. The medial condyle is difficult to fix through the lateral incision. In this case, an additional anteromedial incision is required to reduce and fix the Hoffa fracture. In any case, all major condylar bone fragments are fixed with lag screws after anatomical reduction of the condyle.
- Surgical method The patient is in the supine position on a fluoroscopic bed with a tourniquet. A bolster is used to maintain the knee flexion angle of about 90°. For simple medial Hoffa fractures, the author prefers to use a median incision with a medial parapatellar approach. For lateral Hoffa fractures, a lateral incision is used. Some doctors suggest that a lateral parapatellar approach is also a reasonable choice. Once the fracture ends are exposed, routine exploration is performed, and then the fracture ends are cleaned with a curette. Under direct vision, reduction is performed using a point reduction forceps. If necessary, the “joystick” technique of Kirschner wires is used for reduction, and then the Kirschner wires are used for reduction and fixation to prevent fracture displacement, but the Kirschner wires cannot hinder the implantation of other screws (Figure 3). Use at least two screws to achieve stable fixation and interfragmentary compression. Drill perpendicular to the fracture and away from the patellofemoral joint. Avoid drilling into the posterior joint cavity, preferably with C-arm fluoroscopy. Screws are placed with or without washers as needed. The screws should be countersunk and of sufficient length to fix the subarticular cartilage. Intraoperatively, the knee is inspected for concomitant injuries, stability, and range of motion, and a thorough irrigation is performed before wound closure.
Figure 3 Temporary reduction and fixation of bicondylar Hoffa fractures with Kirschner wires during surgery, using Kirschner wires to pry the bone fragments
Post time: Mar-12-2025
